This is the first in a series of reports ranking each position in the NFL.

When an NFL scout evaluates a running back, the player's size, power, speed, durability and versatility all play a role in the overall assessment. Sporting News enlisted an NFL team's director of pro personnel to rank and analyze the top 20 backs based on those criteria:

1. Adrian Peterson, Vikings. He has a slight edge on Chris Johnson because he's a more physical pure power runner—and also has breakaway speed. He's working to solve issues with ball security.

2. Chris Johnson, Titans. In addition to tremendous speed, he has great body control. Although he is slightly lighter and shorter than ideal, he runs like he's bigger.

3. Steven Jackson, Rams. A big man (6-2, 231) who has amazing versatility and deceptive speed to go with sudden bursts of power.

4. Ronnie Brown, Dolphins. If it weren't for durability issues, he might be the complete NFL back. Like Jackson, he has a big body (6-0, 230) and is a good receiver. Brown has shown he can throw the ball, too.

6. DeAngelo Williams, Panthers. He runs with good power and speed thanks to strong legs. He's a home run threat on every down.

7. Frank Gore, 49ers. With his compact frame, he's in the same category as Williams. He has outstanding vision to go with speed and ability to break tackles.

8. Maurice Jones-Drew, Jaguars. Another smaller back who has powerful legs that make him tough to bring down. He excels on screens and draws.

9. Brandon Jacobs, Giants. A big, bruising back coming off a struggle in 2009. He takes a lot of hits with his upright style but delivers them, too.

10. Felix Jones, Cowboys. He fits well in Dallas' scheme and his great speed is obvious, but he can also be a good power back with deceptive strength.

11. Marshawn Lynch, Bills. Looking at him purely on the field, he is very skilled and powerful. He must show he can avoid the injury bug, however, to maintain success in Buffalo or elsewhere.

12. Marion Barber, Cowboys. He always runs with a head of steam at 100 miles per hour. He knows he's big and strong and takes it out on you.

13. Cedric Benson, Bengals. He had a bad start to his career but turned the corner last year. Now, like Lynch, he just needs to get out of his own way.

14. Reggie Bush, Saints. A little change of pace here—his elusiveness stands out as both a runner and receiver. He's a great asset on screens and draws.

15. Rashard Mendenhall, Steelers. He fits the mold of a big, strong, fast back and may be ready for a breakout year with better help from his line.

16. Ray Rice, Ravens. They asked him do a lot last season, and he held up. That will be key going forward, because with his size (5-8, 205) they need to keep him from getting him too nicked up as a feature back.

17. Shonn Greene, Jets. You could have called him a dark horse to find the light in Year 2, but then you remember how great he was during the playoffs.

18. Matt Forte, Bears. He had a big rookie year before the workload caught up to him a bit in Year 2. His powerful body and versatility still stand out. Having Chester Taylor to relieve him should help.

19. Beanie Wells, Cardinals. He's a big back, but he also has the burst to rack up big yards per carry. Getting double-digit touches consistently this season will help him.

20. Jonathan Stewart, Panthers. They don't miss a beat when he replaces Williams; he would be a featured star on most teams.

Six talented backs who didn't quite make the cut:

Joseph Addai, Colts. It's hard to get a read on him in the Colts'offense. He may lose significant touches to Donald Brown.

Jamaal Charles, Chiefs. The little back surprised many with a big second half of the season. The Chiefs made a good move to bring in Thomas Jones, who will help keep Charles fresh and healthy.

Ryan Grant, Packers. He can be explosive, but his success may have more to do with his cutback running, which is ideal for his team's scheme.

LeSean McCoy, Eagles. He has the versatile skills to be a younger Brian Westbrook; he just needs to prove it.

Knowshon Moreno, Broncos. Moreno was nicked up a lot as a rookie, so it will take another year to determine just how good he is.

I understand that Ricky is old.... but I think he is a better back than some of those towards the bottom....

Maybe comparable to the unproven Shonn Green, although I can see where youth and promise can outweigh veteran experience.... Jonathan Stewart? well I think Ricky is more complete, and had a better year last year, and should do so again this year...... Beanie Wells? really? better than Ricky.... wow, just cause he was on a few top 10 college teams makes him a top 20 back, pfft... Forte? well i like him, but still... if it came down to it, I would chose Ricky over any of those 4...

As for Ronnie.... fair assessment of him. Ronnie is a one of a kind back, all the power you want, and enough burst. His top speed though is his ONLY downside as far as skills, many defenders have caught him from the back on the rare long runs in his career. But otherwise, pass catching, throwing ability, ability to lay the lumber, elusiveness, patience.... its all there. Injuries are his only major flaw..... Honestly, I wouldnt put him in the top 5 because of such..... Miami CANT rely on him, no matter how bad we all want to, it's been 4 years, and he's completed only 1 season! Id still fit him into the top 10 though.... with Ricky at 15

as a runningback, Ray Rice is at 16. I can understand that, and as one of his biggest fans (and classmates) that is acceptable..... as an OVERALL FOOTBALL PLAYER... Id put him in a top 5 list........He does SOOO much outside of his RB position that it overshadows his RB game.... I mean think about it, his short yardage game is average at best. If your team is up by 4, with the ball and 4 minutes to play, your not gonna force feed Ray ray.... you'll give it to Mcgahee or McClain. Not saying that he isnt a dependable back, but he's got that Reggie Bush-ness but 10 times better.

The fact that Reggie is on this list is absurd. He is barely a RB to begin with

1. Chris Johnson- 4.2 speed, low to the ground, and can score every time he touches the football. 2k isn't just a name, it's a ridiculous amount of yards that few have seen.2. Adrian Peterson- When he was drafted, I figured he'd be in Ronnie Brown company: Elite, but often injured. Instead, he's been elite/great, but fumble prone. Therefore, I knocked him to number 2.3. Steven Jackson- He plays for a bad team, but in a league where it's vogue to have two RB's, he is still in the mold of 2005 or earlier and carries his team on the ground and the occasional check down pass.4. MJD- Small back, big legs. He can get under a defender and carry them for seven more yards. Another feature back.5. Michael Turner- I put all the feature backs at the top of the list, because that shows that they can be in the game for the whole game. Michael Turner was a two-back guy with LT, but his first season alone he blew up the league. An injury set him back, so number 5 seems fitting.6. Frank Gore- A powerful back that can carry his team. Nothing flashy, just good old fashioned hard running...which is what Singletary enjoys, so he should have a great year.7. DeAngelo Williams- He holds the NCAA record for most all-purpose yards. This guy can play.8. Ray Rice- 2000 all-purpose yards. Is he top 5? Probably not, because he definitely benefits from playing in Cameron's system (that hurt dearly to say that).9. Johnathon Stewart/Reshard Mendenhall- These are sort of the same back in my opinion. Then again, this whole thing is my opinion, so I'm being redundant.10. Ronnie Brown- Great if healthy, non effective when not..obviously.11. Ricky Williams- He's still got it. He'd be top 5 if he were the feature back, but if he were the feature back, he'd probably wear down. Either way, he's a starter on almost every other team.12. Shonn Greene- Watched a lot of him in college. Does he have breakaway speed?-Asked the NFL scouts. Well, let the San Diego playoff game speak for that...however, not a lot of carries to be able to put him in the top 10 yet.13. Matt Forte- He's a one cut back, with great hands. He should play well with Mike Martz.14. Jamaal Charles- This kid is going to be a stud. I was amazed at his speed when he first got to KC, and Miami fans know first hand that when he gets the ball in his hands, he's a major threat. He's all over the field, catching, and most notably running wild in Denver.15. Justin Forsett- Another runner that can catch. I enjoyed watching his powerful running at Cal, and he's proved be an excellent back in Seattle. He probably won't ever hit the 1000 yard mark rushing, but his all-purpose yardage will help whoever he plays to move the ball.16. Pierre Thomas- Probably one of the most underrated players in the NFL. He plays second fiddle to Reggie Bush even though he sees a great bulk of the carries. He's a stud as a runner.17. Marion Barber- Runs high, but still is able to put the lick on the defender. Felix Jones isn't on the list because he hasn't shown the tenacity of Barber, but Jones has the quick burst. Of the two backs, I like Barber, but they work great together.18. Ryan Grant- A feature back on one of the top offensive teams in the league. He has to be in the top 20.19. Darren McFadden- A bust? Who in Oakland isn't considered a bust? Get him out of there and you'll see one of the league's best backs, but because he's unmotivated (as is the entire organization) we hear about the bust. But if you've actually watched him run, you'd know that if he had at least one guy blocking hard for him, he could go the distance on every carry.20. Darren Sproles- Can catch, can run, and return punts and kicks. He constantly gets knocked for his lack of size, but his play has never shown he can't take a beating. 200+ rushing yards and 300 all-purpose yards against Indy in the playoffs doesn't happen to just any back (Lamar Smith?). Maybe, it's just the Colts D, eh?

Almost, but not quite:Ryan Matthews- He's a rookie, what can I say?

Felix Jones- Most people he's in the top 15, but I honestly haven't seen him play enough...he seems to me to be a guy that will always play well with others and never be able to take the full load, unlike his former teammate McFadden.

Thomas Jones- 1400 yards last year, and he didn't seem to lose a step. However, I expect his age and the wear and tear to catch up with him at some point this season. But that's what Jamaal Charles is for.

Cedric Benson- Until he's able to put back to back good seasons together, I'll always consider this guy a bust. His arrest in Texas recently doesn't bode well for him either.

Jerome Harrison- A one-hit wonder?

Clinton Portis- All this guy has done is post 1500 or more all-purpose yards for 6 of his 8 seasons. However, the injury last year limited him to just 8 games and 400 yards, and the consistent 325+ carry seasons he's had leads me to believe his prime is in the rear view mirror.

As for LeSean McCoy, I guess nothing he's done has impressed me. About 900 yards in all-purpose yardage. Maybe if he performs well this coming season, but one year and nothing flashy isn't enough to constitute a top 20 player.

I can't argue with most of that list, iowa...but how can you put Stewart and Mendenhall over Ronnie?

Also, Greene had a good post season...Pierre Thomas has been stellar all around for the Saints for multiple seasons now. I would have put him over Greene.

But like I said, I can't argue with most of it.

Thomas over Greene makes sense. As for Stewart and Mendenhall over Brown? They both had stellar second seasons in the league last year, Stewart had a YPC of 5.1...a feat that Brown only mustered once, and that was only through 8 games. Mendenhall also hit a 4.6 YPC..which again is a feat Brown only beat in 2007. And Mendenhall did it with a completely atrocious offensive line.

Is Brown an excellent back? Yes, but he's got to stay healthy and be consistent. Stewart and Mendenhall have the consistency to work on, but in just the one year they did better than Brown has done in his 5 years.

I can't argue with most of that list, iowa...but how can you put Stewart and Mendenhall over Ronnie?

Also, Greene had a good post season...Pierre Thomas has been stellar all around for the Saints for multiple seasons now. I would have put him over Greene.

But like I said, I can't argue with most of it.

Thomas over Greene makes sense. As for Stewart and Mendenhall over Brown? They both had stellar second seasons in the league last year, Stewart had a YPC of 5.1...a feat that Brown only mustered once, and that was only through 8 games. Mendenhall also hit a 4.6 YPC..which again is a feat Brown only beat in 2007. And Mendenhall did it with a completely atrocious offensive line.

Is Brown an excellent back? Yes, but he's got to stay healthy and be consistent. Stewart and Mendenhall have the consistency to work on, but in just the one year they did better than Brown has done in his 5 years.

It amazes me that Stewart has been able to amass such numbers in a secondary role. Pretty impressive.

I think if you're going to put the likes of Forsett and McFadden on there you should probably include Addai and McCoy... but again its just a small change there, none of them are all-stars at this point.

I can't argue with most of that list, iowa...but how can you put Stewart and Mendenhall over Ronnie?

Also, Greene had a good post season...Pierre Thomas has been stellar all around for the Saints for multiple seasons now. I would have put him over Greene.

But like I said, I can't argue with most of it.

Thomas over Greene makes sense. As for Stewart and Mendenhall over Brown? They both had stellar second seasons in the league last year, Stewart had a YPC of 5.1...a feat that Brown only mustered once, and that was only through 8 games. Mendenhall also hit a 4.6 YPC..which again is a feat Brown only beat in 2007. And Mendenhall did it with a completely atrocious offensive line.

Is Brown an excellent back? Yes, but he's got to stay healthy and be consistent. Stewart and Mendenhall have the consistency to work on, but in just the one year they did better than Brown has done in his 5 years.

If Ronnie Brown was to DeAngelo Williams what Stewart is to him, or even what Ricky is to RB, he would also be getting 5.1 ypc.

Mendenhall is a good runner, but where is the versatility? Whenever I watch him play he just does not have it receiving wise, and is not a very good blocker-picker-upper (something I believe Ronnie is best in the league at for a tailback). He's a one trick pony. Ronnie can do many more jobs for your offense than Mendenhall. He also had a much better passing game to open things up for him.

I can't argue with most of that list, iowa...but how can you put Stewart and Mendenhall over Ronnie?

Also, Greene had a good post season...Pierre Thomas has been stellar all around for the Saints for multiple seasons now. I would have put him over Greene.

But like I said, I can't argue with most of it.

Thomas over Greene makes sense. As for Stewart and Mendenhall over Brown? They both had stellar second seasons in the league last year, Stewart had a YPC of 5.1...a feat that Brown only mustered once, and that was only through 8 games. Mendenhall also hit a 4.6 YPC..which again is a feat Brown only beat in 2007. And Mendenhall did it with a completely atrocious offensive line.

Is Brown an excellent back? Yes, but he's got to stay healthy and be consistent. Stewart and Mendenhall have the consistency to work on, but in just the one year they did better than Brown has done in his 5 years.

If Ronnie Brown was to DeAngelo Williams what Stewart is to him, or even what Ricky is to RB, he would also be getting 5.1 ypc.

Mendenhall is a good runner, but where is the versatility? Whenever I watch him play he just does not have it receiving wise, and is not a very good blocker-picker-upper (something I believe Ronnie is best in the league at for a tailback). He's a one trick pony. Ronnie can do many more jobs for your offense than Mendenhall. He also had a much better passing game to open things up for him.

But if we're talking ypc, shouldn't Ricky also be higher than Ronnie?

You lost me on that first sentence. Mendenhall essentially had his first year last year, so his pass assignments should improve...as for receiving, that's unfair considering he isn't asked to do that the majority of the time. The Steelers play action to the back and go to the receivers/tight ends.

As far as the RIcky/Ronnie...they are right by each other. Don't be nit picky.

What I meant was that if Ronnie was spelling DeAngelo Williams like Jonathon Stewart does, Ronnie would too have a 5.1 ypc. Ronnie is the feature back here, though, and bruises defenses opening things up for Ricky. If Ronnie was the change of pace he would be getting more production per pop.

1. Chris Johnson- 4.2 speed, low to the ground, and can score every time he touches the football. 2k isn't just a name, it's a ridiculous amount of yards that few have seen.2. Adrian Peterson- When he was drafted, I figured he'd be in Ronnie Brown company: Elite, but often injured. Instead, he's been elite/great, but fumble prone. Therefore, I knocked him to number 2.3. Steven Jackson- He plays for a bad team, but in a league where it's vogue to have two RB's, he is still in the mold of 2005 or earlier and carries his team on the ground and the occasional check down pass.4. MJD- Small back, big legs. He can get under a defender and carry them for seven more yards. Another feature back.5. Michael Turner- I put all the feature backs at the top of the list, because that shows that they can be in the game for the whole game. Michael Turner was a two-back guy with LT, but his first season alone he blew up the league. An injury set him back, so number 5 seems fitting.6. Frank Gore- A powerful back that can carry his team. Nothing flashy, just good old fashioned hard running...which is what Singletary enjoys, so he should have a great year.7. DeAngelo Williams- He holds the NCAA record for most all-purpose yards. This guy can play.8. Ray Rice- 2000 all-purpose yards. Is he top 5? Probably not, because he definitely benefits from playing in Cameron's system (that hurt dearly to say that).9. Johnathon Stewart/Reshard Mendenhall- These are sort of the same back in my opinion. Then again, this whole thing is my opinion, so I'm being redundant.10. Ronnie Brown- Great if healthy, non effective when not..obviously.11. Ricky Williams- He's still got it. He'd be top 5 if he were the feature back, but if he were the feature back, he'd probably wear down. Either way, he's a starter on almost every other team.12. Shonn Greene- Watched a lot of him in college. Does he have breakaway speed?-Asked the NFL scouts. Well, let the San Diego playoff game speak for that...however, not a lot of carries to be able to put him in the top 10 yet.13. Matt Forte- He's a one cut back, with great hands. He should play well with Mike Martz.14. Jamaal Charles- This kid is going to be a stud. I was amazed at his speed when he first got to KC, and Miami fans know first hand that when he gets the ball in his hands, he's a major threat. He's all over the field, catching, and most notably running wild in Denver.15. Justin Forsett- Another runner that can catch. I enjoyed watching his powerful running at Cal, and he's proved be an excellent back in Seattle. He probably won't ever hit the 1000 yard mark rushing, but his all-purpose yardage will help whoever he plays to move the ball.16. Pierre Thomas- Probably one of the most underrated players in the NFL. He plays second fiddle to Reggie Bush even though he sees a great bulk of the carries. He's a stud as a runner.17. Marion Barber- Runs high, but still is able to put the lick on the defender. Felix Jones isn't on the list because he hasn't shown the tenacity of Barber, but Jones has the quick burst. Of the two backs, I like Barber, but they work great together.18. Ryan Grant- A feature back on one of the top offensive teams in the league. He has to be in the top 20.19. Darren McFadden- A bust? Who in Oakland isn't considered a bust? Get him out of there and you'll see one of the league's best backs, but because he's unmotivated (as is the entire organization) we hear about the bust. But if you've actually watched him run, you'd know that if he had at least one guy blocking hard for him, he could go the distance on every carry.20. Darren Sproles- Can catch, can run, and return punts and kicks. He constantly gets knocked for his lack of size, but his play has never shown he can't take a beating. 200+ rushing yards and 300 all-purpose yards against Indy in the playoffs doesn't happen to just any back (Lamar Smith?). Maybe, it's just the Colts D, eh?

Almost, but not quite:Ryan Matthews- He's a rookie, what can I say?

Felix Jones- Most people he's in the top 15, but I honestly haven't seen him play enough...he seems to me to be a guy that will always play well with others and never be able to take the full load, unlike his former teammate McFadden.

Thomas Jones- 1400 yards last year, and he didn't seem to lose a step. However, I expect his age and the wear and tear to catch up with him at some point this season. But that's what Jamaal Charles is for.

Cedric Benson- Until he's able to put back to back good seasons together, I'll always consider this guy a bust. His arrest in Texas recently doesn't bode well for him either.

Jerome Harrison- A one-hit wonder?

Clinton Portis- All this guy has done is post 1500 or more all-purpose yards for 6 of his 8 seasons. However, the injury last year limited him to just 8 games and 400 yards, and the consistent 325+ carry seasons he's had leads me to believe his prime is in the rear view mirror.

Very solid list. I need to see how Shonn Greene for a full season before I put him that high. I think Jamaal Charles could be a special back.

Ronnie Brown has the potential to be a top 5 back easily, as he can do it all. But, and you hate to continue to say it, but it is very true. He has to stay healthy and be on the field, and there no getting around that.

Agree very much with Ricky being in the top 15. Ricky is still big, fast and explosive and has very good hands in the passing game as well. The only drawback with Ricky at this point is his age.